A self-regulating glare protection system using concentrated solar radiation and thermotropic coating

A static, non-mechanical, self-activating sun protection system affecting t he direct sunlight but not the diffuse skylight is described It is based on the selection of direct sunlight by concentration. A lens array in front o f a glass' anc concentrates the direct light onto a thermotropic layer wher e it increases temperature beyond the switching temperature and causes the thermotropic layer to become locally quasi-opaque. Most parts of the glazin g except for the small focal regions remain transparent and contribute to t he illumination of the room behind. The system performance is theoretically analysed by a numerical solution of the equation of heat conduction, givin g the temperature distribution within the system. Different samples of the sun protection system, using different thermotropic materials and other sys tem components have been constructed and measurements of various temperatur e and transmission properties have been performed. (C) 2001 Elsevier Scienc e Ltd. All rights reserved.